Electric discharge vessel



ELECTRIC DISCHARGE vEssEL Filed Jan. 2C, 1940 Patented Apr. 21, 1942 i UNlTEosTATE b ELECTRIC DISCHARGE VESSEL Rudolfv Scharfnagel, Stuttgart, Germany, assign-` or to C. Lorenz Aktiengesellschaft, Berlin-Tempelhof, Germany, a' company j Appueatibn January 26,1940, serialivoisisyi y In. Germany February 9, 1939 l g Claims.

the influence of rapid changes of temperature A bad heat conductorsl have been arranged or means have been provided tolead the vheat ow past such seals, or still other means adapted to ,effect the desired thermal relief havev been employed, such for instance "as resistances to heat flow. However, any means of this kind is effective only with larger-sized Vacuum apparatus,

such as discharge tubes or the like. Such means must be large in relation to the dimensionsof these' devices and largeespecially as compared with the seals to be protected thereby, thus also being comparatively heavy, and hence cannot be applied to somewhat small discharge tubes. In

addition, the heat radiation from a highly heated part of thedischarge tubes, such as a wall portion thereof constituting the anode, in the case of small tubes will not be prevented vfrom impairing the seal if the protective means consists in resistances to heat interposed between the two.

As is well-known, discharge vessels in which the bulb or envelope is entirely or in part made of a metal in order to serve as anode, may be heavily loaded. The load may be such that this envelope or .bulb will become red hot. However, in order to allow of such a high load the envelope is required not to be porous when red hot since otherwise the vacuum would be impaired. In

t addition a second requirement is to be fullled,

namely, that the cover of the vessel and the sealing means, this being usually of a vitreous material, should be protected from the resultant quick changes of temperature and from nonuniform distribution of temperature.

The invention is concerned with this second requirement, as will be understood from the following description, reference being had to the accompanying drawing, which shows a somewhat diagrammatic fragmentary sectional view of an example of discharge vessels as provided by the vIn order to protect heat-sensitive sealsapplied to vacuum apparatus, `such as"glass seals,v from which is porous or ispiercedwith holes in wellknown manner. The -leads Gare sealed by means of a glass ,layer 4. arrangedto cover also the joints between the parts 1, 5, I. l

In this way the cover 1, 4 forbulb2, I, 3 is separated from the anode 42A by ring 5 and enlargement I.Owing to the shape and wall thickness of the assembly I, 5 this separation'is such that the thermal behaviour of the anode 2 will .be different from that Lof cover 1v, 4. In fact, quick variations oftemperature of the anode, this being substantially free from thermal inertia, and especially thejabrupt rise ,in tem- Vperature thereof `on loadingvthe discharge vessel, arel preventedby the separating or ,screening means I, 5 fromv affectingv the cover l, 4,

while the thermal inertia of cover -`I, 4 willin its turn decrease temperature variations thereof. The novel arrangementinithis way acts to minimize the heat transferredv fromthe anode to seal 4and hence allows ythis seal tohbe made of a low-melting material, such as a soft glass, for instance.

Furthermore, the heat from the glowing anode..v

2 will be transferred by ring 5 directly to the middle of the glass layer 4, or nearly so, whereas in prior devices this layer is heated from its edge only. Ring 5 thus acts to minimize differences of temperature inthe layer 4. The ceramic disc 1, arranged to contact with ring 5, will thus aid in distributing the heat, so as to prevent strains in the glass layer and hence to obviate the formation of cracks therein even if the layer 4 be composed of a number of vitreous layers whose coe'flicientsof expansion are diierent from each other. Such will be the case also with pulsating loads onthe discharge vessel which cause the anode to become bright red hot. The invention will hence be useful also in the mass production of such devices.

Ring 5 need not be of a metallic material but suitable insulating may be a ceramic or vother body.

The fact that the seal 4 is protected from being unduly heated is of advantage especially in the case of complicated seals or seals diflicult to produce free from strains. Devices of this kind are those having two or more seals fitted to a metal bulb and spaced apart by a comparatively small distance and which are not applied to the bulbv all at. the same time but are applied one after another.

The ring 5, serving as a heat accumulating means, is useful also inasmuch as it acts to retard the cooling down of the glass layer 4`when thermal inertia and constituting the anode, and Y a second part which carries the leads and iis'.

possessed of high thermal inertia on account of its great heat capacity, this part being the cover for the discharge vessel, l

Appropriately bulb 2, I-, V3 Fis manufactured by using a method that avoids chip waste.` 'In such case ring 5 or another .auxiliary body, em-

ployed instead thereof, may be pressed into. Atheenlargement I while producing the bulb in this way.

-What islclaimed is:

1. Anenvelope `for an electric discharge vesselprovided with anopening, said envelope comprising a part having -a relatively thin wall substantially free from thermal inertia and a section having a thicker walldi'sposed between said part and said opening,l a metalsring contacting the wall of said vessel disposed within said tube at the opening therein, said' ring vand said section cooperating to minimizeA ,ther effectvof `sudden thermal changes inthe thin @walled part of the tube on the edge of the opening.

2.' An envelope. forvan 'electric discharge vessel provided with an opening, said envelope com.- prising a part having a relatively thin Wall substantially freefrom thermal inertia and a section having a thicker Wall disposed between said part and saidv opening,.a metal ring` contacting the wall of .saidv vessel-.disposed Within ,said tube at the opening.,therein a tceramic disc disposed within said ringand'airneinber arranged to seal said opening and engagel said.. .ring -and disc whereby heat from. said envelope is uniformly distributed to said member.

3. An envelope for an electric discharge Vessel provided with an opening, said envelope comprising a part having a relatively thin wall substantially free from thermal inertia and a section having a thicker wall disposed between said part and said opening, a metal ring 4contacting the wall of said vessel disposed Within said tube 410 v@at the opening therein, a member for sealing said opening; said ring and the edge of said opening'insaid envelope cooperating to minimize the effect ofsudden :thermal changes in the thin f walled part .of the tube and to distribute heat uniformly. toisaid seal.

4. An electric ,discharge vessel comprising elec- ".trodes and a metallic envelope therefor, said envelope being formed with thin walls adjacent to said electrodes and considerably thicker walls between said electrodes and said opening,y a metallic ring closely 'tting inside said tube' dis posed flushwith the edge of saidopeningja 'disc yof ceramic material disposed within said ringiand a member adapted to seal said ring and disc 'to thev` opening in said envelope.

5. An electric ...discharge vessel `comprising electrode means and a metallicl envelope` therefor provided with an opening, the walls of vsaidjenvelope adjacent to said electrode means being thin and relatively free fromA thermal inertia, while the part of the wall kof the envelopey be,-

ltween said opening and said electrode means is considerably thicker, a metal' ring disposed within said tube so that the edge thereof Vis vflush with the edge of. said opening, and means to seal jsaid opening, the .arrangement vvbeingsuch that the ring cooperates with the'thicker .portion of the 'wall of saidenvelope.tominimize theeiiect o f vtemperature variationsjof. the thinner -part and distribute heat evenly to. said sealing means.

' scrimmage@ 

